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[CALCITE-4693] Query with Lateral Join should converted to Left Join … #4474

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[CALCITE-4693] Query with Lateral Join should converted to Left Join … #4474

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[CALCITE-4693] Query with Lateral Join should converted to Left Join …
NobiGo Jul 22, 2025
b7278f3
[CALCITE-4693] Code Review
NobiGo Jul 23, 2025
f55e538
[CALCITE-4693] Add Unit Test can't Pass
NobiGo Jul 25, 2025
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23 changes: 23 additions & 0 deletions core/src/main/java/org/apache/calcite/sql/validate/SqlValidatorImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1418,6 +1418,29 @@ private void handleOffsetFetch(@Nullable SqlNode offset, @Nullable SqlNode fetch
if (node instanceof SqlMerge) {
validatingSqlMerge = true;
}
if (node instanceof SqlJoin) {
// select * from "scott".dept,
// lateral (select count(cast(deptno as integer)) from "scott".emp
// where emp.deptno = dept.deptno);
// ==》
// select * from "scott".dept left join
// lateral (select count(cast(deptno as integer)) from "scott".emp
// where emp.deptno = dept.deptno) on true;
SqlJoin sqlJoin = (SqlJoin) node;
if (sqlJoin.getJoinType() == JoinType.COMMA && sqlJoin.getRight() instanceof SqlCall) {
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@mihaibudiu mihaibudiu Jul 23, 2025

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can you explain where the discussion in the JIRA is reflected in this code?
I think the consensus there was that a left join is not always right

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@julianhyde julianhyde Jul 24, 2025

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I agree, @mihaibudiu. The jira cases discusses how converting an inner lateral join to a left join is WRONG. Do not merge this PR.

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@NobiGo NobiGo Jul 25, 2025

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I will recheck this. This repair method does have some issues. I will add more test cases to verify it.

SqlCall sqlCall = (SqlCall) sqlJoin.getRight();
if (sqlCall.getOperator() == SqlStdOperatorTable.LATERAL
&& sqlCall.operand(0) instanceof SqlSelect
&& isAggregate(sqlCall.operand(0))) {
return performUnconditionalRewrites(
new SqlJoin(sqlJoin.getParserPosition(),
sqlJoin.getLeft(), sqlJoin.isNaturalNode(),
JoinType.LEFT.symbol(node.getParserPosition()),
sqlJoin.getRight(), JoinConditionType.ON.symbol(node.getParserPosition()),
SqlLiteral.createBoolean(true, node.getParserPosition())), underFrom);
}
}
}
SqlCall call = (SqlCall) node;
final SqlKind kind = call.getKind();
final List<SqlNode> operands = call.getOperandList();
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82 changes: 82 additions & 0 deletions core/src/test/resources/sql/lateral.iq
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Expand Up @@ -246,4 +246,86 @@ where job = 'MANAGER';

!ok

# [CALCITE-4693] Query with Lateral Join should converted to Left Join When sub-query is aggregate query

select * from "scott".dept, lateral (select count(cast(deptno as integer)) from "scott".emp where emp.deptno = dept.deptno);

SELECT "DEPT"."DEPTNO", "DEPT"."DNAME", "DEPT"."LOC", "EXPR$0"."EXPR$0"
FROM "scott"."DEPT" AS "DEPT"
LEFT JOIN (SELECT COUNT(CAST("EMP"."DEPTNO" AS INTEGER))
FROM "scott"."EMP" AS "EMP"
WHERE "EMP"."DEPTNO" = "DEPT"."DEPTNO") AS "EXPR$0" ON TRUE
!explain-validated-on calcite
+--------+------------+----------+--------+
| DEPTNO | DNAME | LOC | EXPR$0 |
+--------+------------+----------+--------+
| 10 | ACCOUNTING | NEW YORK | 3 |
| 20 | RESEARCH | DALLAS | 5 |
| 30 | SALES | CHICAGO | 6 |
| 40 | OPERATIONS | BOSTON | 0 |
+--------+------------+----------+--------+
(4 rows)

!ok

select * from "scott".dept, lateral (select count(cast(deptno as integer)) from "scott".emp where emp.deptno = dept.deptno + 10);

SELECT "DEPT"."DEPTNO", "DEPT"."DNAME", "DEPT"."LOC", "EXPR$0"."EXPR$0"
FROM "scott"."DEPT" AS "DEPT"
LEFT JOIN (SELECT COUNT(CAST("EMP"."DEPTNO" AS INTEGER))
FROM "scott"."EMP" AS "EMP"
WHERE CAST("EMP"."DEPTNO" AS INTEGER) = "DEPT"."DEPTNO" + 10) AS "EXPR$0" ON TRUE
!explain-validated-on calcite
+--------+------------+----------+--------+
| DEPTNO | DNAME | LOC | EXPR$0 |
+--------+------------+----------+--------+
| 10 | ACCOUNTING | NEW YORK | 5 |
| 20 | RESEARCH | DALLAS | 6 |
| 30 | SALES | CHICAGO | 0 |
| 40 | OPERATIONS | BOSTON | 0 |
+--------+------------+----------+--------+
(4 rows)

!ok

select * from "scott".dept, lateral (select sum(cast(deptno as integer)) from "scott".emp where emp.deptno = dept.deptno);

SELECT "DEPT"."DEPTNO", "DEPT"."DNAME", "DEPT"."LOC", "EXPR$0"."EXPR$0"
FROM "scott"."DEPT" AS "DEPT"
LEFT JOIN (SELECT SUM(CAST("EMP"."DEPTNO" AS INTEGER))
FROM "scott"."EMP" AS "EMP"
WHERE "EMP"."DEPTNO" = "DEPT"."DEPTNO") AS "EXPR$0" ON TRUE
!explain-validated-on calcite
+--------+------------+----------+--------+
| DEPTNO | DNAME | LOC | EXPR$0 |
+--------+------------+----------+--------+
| 10 | ACCOUNTING | NEW YORK | 30 |
| 20 | RESEARCH | DALLAS | 100 |
| 30 | SALES | CHICAGO | 180 |
| 40 | OPERATIONS | BOSTON | |
+--------+------------+----------+--------+
(4 rows)

!ok

select * from "scott".dept, lateral (select sum(cast(deptno as integer)) from "scott".emp where emp.deptno = dept.deptno + 10);

SELECT "DEPT"."DEPTNO", "DEPT"."DNAME", "DEPT"."LOC", "EXPR$0"."EXPR$0"
FROM "scott"."DEPT" AS "DEPT"
LEFT JOIN (SELECT SUM(CAST("EMP"."DEPTNO" AS INTEGER))
FROM "scott"."EMP" AS "EMP"
WHERE CAST("EMP"."DEPTNO" AS INTEGER) = "DEPT"."DEPTNO" + 10) AS "EXPR$0" ON TRUE
!explain-validated-on calcite
+--------+------------+----------+--------+
| DEPTNO | DNAME | LOC | EXPR$0 |
+--------+------------+----------+--------+
| 10 | ACCOUNTING | NEW YORK | 100 |
| 20 | RESEARCH | DALLAS | 180 |
| 30 | SALES | CHICAGO | |
| 40 | OPERATIONS | BOSTON | |
+--------+------------+----------+--------+
(4 rows)

!ok

# End lateral.iq
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